You must be very new on Daz or how you still don't know this basic stuff.
You do not need a model with genitalia you add genitalia separately.
You can either use golden place" or "new genitalia for Victoria"
then find Zexpansion morphs and other related stuff.
You may want to squeeze it to make look more adequate for a child
I would recommend you to go here https://3d-load.net/
to find more models for all purposes.
To know what to look for, go here for a list of good looking child models
they are all available online.
Later you can combine shapes and skins from different models to get desired results
you can also adjust eye angle a bit to make a character look more naive/innocent, neutral or dominant/evil
Unfortunately, it is problematic to find good boy models